Track

Case Reports

Abstract

Post-transplant lymphoproliferative disorders (PTLD) comprise a diverse and heterogeneous group of lymphoid proliferations and neoplasms arising in the setting of iatrogenic immunosuppression. T-cell PTLDs (T-PTLD) account for less than 15% of cases, are often EBV-negative, and rarely present with skin-limited disease, particularly after hematopoietic stem cell transplantation (HSCT). We report a case of EBV-negative, monomorphic T-PTLD with cutaneous involvement that closely resembled mycosis fungoides (MF) histologically. A 52-year-old male developed multiple annular hypopigmented patches on the extremities 260 days after haploidentical HSCT for acute myeloid leukemia. Initial and repeat biopsies demonstrated epidermotropism, folliculotropism, cytologic atypia, negative EBER in situ hybridization, and lymphocytes with partial loss of CD7, CD3+/CD4+/CD8– phenotype. TCR gene rearrangement studies confirmed identical monoclonal TRB and TRG patterns on biopsies from separate sites six weeks apart. Skin chimerism analysis revealed 40% recipient cells. No systemic disease or peripheral blood involvement was detected. The morphologic and immunophenotypic overlap with MF, including epidermotropism and CD7 loss, posed a significant diagnostic challenge. However, the post-transplant context, EBV-negativity, stable monoclonality, and mixed chimerism supported a diagnosis of cutaneous EBV-negative T-PTLD arising from residual host T-cells. Unfortunately, the patient’s course was complicated by infectious sequelae, leading to death from multi-organ failure. This case underscores the importance of integrating histopathologic, molecular, and clinical data in evaluating atypical cutaneous lymphoid infiltrates in immunosuppressed patients. Recognition of T-PTLD as a potential MF mimic is essential to avoid misdiagnosis and ensure appropriate clinical management.